1. Field of the Invention
The present invention relates to a writing or drafting instrument with a writing medium container in the form of an exchangeable cartridge and with a push member which is axially movable in the shaft of the instrument and is used as an ejector, wherein the cartridge is held in the shaft by a clamping action or a positive locking action.
2. Description of the Related Art
Writing or drafting instruments of the above-described type are known in principle. For example, utility models 1 963 329 and 1 920 667, German Patent 30 42 035 and U.S. Pat. No. 3,361,516 illustrate and describe felt tip pens in which a replaceable cartridge held in a shaft by clamping action or positive locking action is utilized as an exchangeable writing medium container. The cartridges have at their rearward ends closing members which can be used as push members or ejectors and which are constructed in such a way that, after the cartridge has been inserted into the shaft, the cartridge axially protrudes beyond the shaft or closes the open end of the shaft. In the forward end of each cartridge is fixedly arranged a fiber wick as writing element.
When the respective cartridge is replaced, the entire cartridge is replaced. This means that it is always necessary to exchange or discard and replace the push member or ejector as well as the writing element together with the empty cartridge, even though these components are usually still in operating condition and could be reused. In the instruments according to German Utility Model 1 920 667 and U.S. Pat. No. 3,361,516, the manipulation during the exchange of the cartridge additionally poses a significant problem because a separate tool is required for ejecting the cartridge from the shaft, wherein the separate tool may be the protective cap.
In addition, German Laid-Open Application 22 08 111 discloses disposable writing utensils which have a spare writing medium reservoir which, when the main writing medium reservoir has become empty, can be connected to the main reservoir by axially actuating a push member so that the writing medium contained in the spare reservoir can flow into the main reservoir, in order to indicate to the user that the entire writing instrument is now being used in "spare operation" and must be replaced soon.
Accordingly, after the writing medium contained in the spare reservoir has been used up, the entire writing instrument must be disposed of.